Object-oriented modelling has become an established technique for product and manufacturing
knowledge representation. Various models offering generalised classes and class hierarchies have been
proposed for this purpose. Additional bespoke classes are however typically required for specific
domain representations. This causes problems when knowledge needs to be shared between domains
using different models to describe common entities. These issues are especially complex when several
systems are involved. For example, a designer accessing product, manufacturing, and third party
systems may face multiple definitions of components, facilities and processes. This paper proposes a
model that addresses some of these issues. The proposed model can describe manufacturing knowledge
without additional bespoke classes. The detailed semantics of the model are based on recent work on
ontologies, notably the Process Specification Language (PSL). Whilst PSL provides detailed semantics,
it is not inherently object-oriented. The integration of PSL with object-oriented modelling methods is
therefore the principle contribution of this work.